JPH073521A - Electret fibers having improved electrification stability, method for producing the same, and fiber material containing these electret fibers - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for producing a fiber having excellent textile fiber properties and improved charge stability with significantly improved half-life of charge. [Structure] To be contained in a toner for electrophotography,
An electret fiber having improved charge stability mainly composed of a fiber-forming polymer or polycondensate, and an organic or organometallic charge control compound, wherein the organic or organometallic charge control compound is
Based on the weight of the material, 0.01 to 30% by weight, preferably 0.01 to 10% by weight, particularly preferably 0.1 to
The electret fiber is 5% by weight, and a method for producing the same.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electret fiber having a considerably improved charge stability because it contains a charge control compound, a process for producing the same, and a fiber material in the form of threads and sheets, and in particular, an improvement thereof. Yarns, tows and non-woven webs composed of or containing electret electrified fibers.

[0002]

2. Description of the Related Art The electret fiber according to the present invention is made of an electrically non-conductive material capable of storing an applied electrostatic charge for a relatively long period of time. A fiber.

Electret fibers have hitherto been mainly used mainly.
It has been described in connection with the problem of filtering very fine dust [eg Biermann, “Evaluation of perman
ently charged eleKtrofibrous filters ", 17, DOE Nuc
lear Air Cleaning Conference, Denver, USA, (1990 /
9) and Chemiefasern / Textilindustrie 40/92 (199
0)]. The filter materials described therein differ from the material from which the fibers are constructed in the manner in which an electrostatic charge is applied to the fibers.

The electrostatic charge can be applied by various methods. Thus, the polymer films can be electrostatically charged differently on both sides and then they can be split. In this case, so-called split film fibers are obtained, which generally
Deposited as a nonwoven fibrous web. Furthermore, fibers or fiber products spun or spun in a strong electrostatic field, such as a non-woven web, are electrically corona-e.g. Between a high voltage point or wire and a grounded surface electrode. It is also known to subject it to a discharge.

Charging by the triboelectric effect is particularly preferred, ie the fibrous material on another medium, eg another polymeric material, a solid, eg a metal surface, or
Charge is separated by alternately rubbing with a liquid or gas medium.

Various fiber materials have been investigated and recommended in the past to produce electret fibers having desirable electret properties, such as long-term charge stability, moisture resistance and chemical resistance. . These advantageous properties should also be achievable at the lowest cost possible. Fluoropolymers, such as polytetrafluoroethylene or perfluorinated ethylene / propylene copolymers, have proven themselves to be very good electret materials, with a half-life of charge (life of charge) of years to several years. Charge stability characterized by decades is combined with good temperature stability and low water absorption. However, the serious drawbacks of these polymers, such as their high price and the great difficulty of their manufacture, have substantially hindered their use.

Electret fibers made of polyolefins such as polyethylene and polypropylene, or polycarbonate have good chemical and moisture resistance. Commercially available very fine dust filters are composed of these electret materials (Chemiefasern / Textilindustrie cited above). A major drawback of these fibers is the relatively low charge half-life, ie, on the order of about a year. This is generally a too short period. For example, when the fiber is used for filter production, considering the time from fiber production to use of the filter, if the filter life is added, it easily becomes 1 year or more. Will end up.

Therefore, as long as electret fibers are recommended and used for the production of very fine filters, they have significantly improved electrostatic stability, humidity and chemical resistance, and good textile fibers ( There is an urgent need to find a less expensive fiber material with textile and mechanical properties, and proposals for it are already becoming known.

In US Pat. No. 4,789,504 it is recommended to enhance the efficacy of polypropylene electret fibers by adding salts of fatty acids to the polymeric material.

Journal of Electrostatics, 24, (1990)
pp. 283-293 shows that when approximately 10% by weight of titanium dioxide is added to the polymer, under standardized measurement conditions,
It is disclosed that the temperature at which the charge density of the polyacrylate electret fiber drops by half increases from 126 ° C to 180 ° C. However, this addition, apart from the loss of mechanical properties, results in an increase in moisture sensitivity which is unsuitable for use in filter materials.

[0011]

[Means for Solving the Problems] Excellent textile fiber properties,
It has been found that it is possible to produce fibers with a significantly increased half-life of the charge, ie with significantly improved charge stability.

The electret fibers according to the invention, which have an improved charge stability, have improved charging properties which are composed of materials which contain organic or organometallic charge control compounds and mainly fiber-forming polymers or polycondensates. An electret fiber having stability, wherein the organic or organometallic charge control compound is 0.
The electret fiber is 01 to 30% by weight, preferably 0.01 to 10% by weight, particularly preferably 0.1 to 5% by weight.

The fiber in the present invention is an endless fiber (filament) or a staple fiber, preferably a staple fiber having a staple length of 0.5 to 50 mm, or a special embodiment for a special use. It is also used to mean pulp, split fiber or split film.

Electret fibers with a low or partial stretch, ie electret fibers with only slight or no stretching, are, like ordinary fibers, mixed fibers for bonding, fixing and stiffening. , Can be used, for example, as a non-woven web;
High shrink electret fibers can be used to increase density and stiffen textile fiber sheet materials, especially nonwoven webs. Multicomponent electret fibers can also be produced in a core-sheath arrangement or a side-by-side arrangement, one of the constituents being the electret fibers according to the invention. For example, “Falkai, Synthesefasern [syntheti
c fibers] ", pages 124 ff. In particular, FIG. 5.4. Multicomponent fibers having electret components according to the present invention have special properties if the components have different heat shrinkage rates. Purpose: For example, if the heat shrinkage of both side-by-side components is different, it can be used as a self-crimping fiber, and if the core of the core-sheath fiber has a relatively low melting point, it can be used as an adhesive fiber. Alternatively, if the cross section of the sea-island fiber has an appropriate arrangement, it can be used as a split fiber for producing an electret fiber having a particularly fine linear density.

A further important core-sheath arrangement of the fibers according to the invention is a core of conventional polymeric material and a sheath of electret material.

In particular, fibers having a high surface area, ie a fine linear density, eg less than 3 dtex, in particular less than 2 dtex, or having a multilobal cross section, eg polygonal or star-shaped cross sections, Or, for example, fibers according to the invention having a ribbon or dumbbell cross section are preferred. The fiber can be processed
For example, as monofilaments, as agglomerates or flocs, as pulp slurry, linear products such as spun fiber yarns, multifilament yarns, tows, slivers, or sheet materials such as staple fibers or random nonwovens of filaments. It can be present as a web, in particular a non-woven fabric or card web, a deposited fabric, a woven fabric or a knitted fabric.

Electret fibers according to the invention in the form of multifilament yarns, tows and nonwoven webs are particularly preferred.

The present invention relates to electrically neutral fibers and fiber products, such as yarns, tows or nonwoven webs, and electrostatically charged fibers and fiber products. In this case, it is immaterial whether, in particular, the charge is applied, for example by a corona discharge, or is naturally generated by a triboelectric effect. The improved electrical properties of the electret fibers according to the invention are essentially due to the characteristic electret behavior of the materials used for their production, but the advantages for their application are electrical,
The combination of mechanical and shape-related properties gives rise to the mass.

The material from which the fibers according to the invention are composed is characterized by improved charge stability. This is manifested in a markedly improved application behavior in all applications in which the presence of electrostatic charges of the fibers plays a positive role, for example in the use of electret fibers according to the invention for the production of dust filters. The improvement of the charge stability is due on the one hand to the improvement of the charge retention, ie through the retention of the once-charged state of charge of the fiber under the application conditions, and on the other hand to the triboelectric effect which results in a kinetic equilibrium of the charge. Achieved according to our previous knowledge, through the effect of complex charge formation. In fact, both effects can possibly influence one another, possibly in different quantitative ratios, so that the polymeric material is mainly contained in the fibrous material.

The effect of improved charge retention is that the material of which the electret fiber according to the present invention is composed has (a) an electric charge of 50 ° C. or higher, preferably 100 to 250.
After the maximum value of the discharge current is exhibited at a temperature of 100 ° C., particularly preferably 100 to 180 ° C., the discharge current curve after reaching the maximum value again shows a significantly descending branch, and (b) 2
Have a half-life of charge of at least 6 months at 5 ° C,
(C) The temperature at which the electric charge is halved is 100 ° C. or higher,
It is preferably 100 to 250 ° C., particularly preferably 10
0-180 ° C., (d) having a charge density of at least 1 × 10 ^-9 coulomb / cm ² after a standard charge (50 μm thick film grounded on the one hand and exposed to corona discharge for 3 minutes). Prove.

The measurement of the discharge current of a material is carried out by circularly depositing a circular sample of a film made from the material and fastened to a holder, metallized on one side by vapor deposition coating with aluminum and grounded. Side to side, charging from the free side by corona discharge for 3 minutes. The sample is then cooled and conditioned at room temperature for 2-3 hours. Then, the electret sample was discharged at a heating rate of 2
℃ / min., “Air gap current TSC (air gap
current TSC) ["Electrets", Editor GM Sessler,
in “Topics in Applied Physics", 2nd edition, (198
7), Vol. 33, pp. 95ff. Springer Verlag. ] "Is measured with the help of the method. During heating, the discharge current is measured and recorded continuously with respect to temperature. Besides the discharge rate, the position of the temperature peak of the discharge current and after the peak The presence of a descending branch of the discharge curve is characteristic of the material.

The half-life of the charge is the period when the charge originally applied to the electret material has been reduced by half at 25 ° C.

The temperature at which the electric charge is halved means a heating rate of 2 ° C.
/ Min. Is used to mean the temperature at which the charge density of the material decreases to half its value at 25 ° C.

Many electret fibers according to the invention surprisingly exhibit a high degree of triboelectric effect, ie they tend to be naturally charged due to their interaction with each other and with their surroundings. Have.
It is composed of these fibers, for example,
Alternatively, a dust filter containing these fibers may pass through a gas (eg, during use) without a separate charge (eg, by corona discharge),
Alternatively, rubbing the fibers against each other or with other types of solids naturally achieves a significantly higher electrostatic charge, thus significantly better than a dust filter ideally constructed with ordinary fibers. Achieve particle separation.

For example, at a distance of a few cm from the filter material, even if no electrostatic field is measured,
It is especially surprising that a significant improvement in the degree of separation of dust particles is made.

Therefore, the relative degree of separation TR% in [%] of the non-woven web filter made of electret fibers according to the invention, which can be easily measured under standard conditions, compared with an ideal filter made of ordinary fibers. The technical improvement represents a very highly relevant parameter for characterizing the improvement of the electrification stability of the electret fibers according to the invention.

To determine the fiber parameter TR%,
Nonwoven web has a weight per unit area of 100 ± 5g /
m ² , fineness 1.7 ± 0.2 dtex, and flow rate 20 cm /
8 seconds pressure difference between upstream and downstream of the filter
Manufactured from electret fibers according to the invention to be tested having a density equal to ~ 12 Pa, which consist of 80% by weight of electret fibers to be tested and 20% by weight of bicomponent binding fibers.

A second non-woven web filter is also produced that is the same in terms of weight per unit area, fineness, and density, but instead of the electret fibers to be investigated, normal fibers (ie, identical fibers). Fiber made of a polymer material, but containing no charge control compound). The degree of separation of both filters is measured for dust particles having an average particle size of 0.3-0.5 μm. T (x) is the resolution of the filter according to the invention, T '(x) is the resolution of the comparison filter,
For values of x from 0.3 to 0.5 μm, TE = ln (1-
When T (x)) and TV = ln (1-T '(x)), TR% is given by the equation: TR% [%] = (TE × 100) / TV-100.

The electret fiber according to the present invention has a TR
% Value of at least 30%, preferably of at least 50
%, For example 40-60%, which have the characteristics given under paragraphs (a)-(d) above, which characterize their charge retention behavior.

For electret fibers according to the invention, which are produced on the basis of polymers having a low charge retention, the TR% value is essentially the triboelectric value for the improvement of the electrification stability of the electret fibers compared to conventional fibers. Characterize the contribution of the effect. The improvement of the charge stability clearly correlates, within certain limits, with the concentration of the charge control compound in the electret fiber material according to the invention. The concentration is set such that the fibers have significantly improved electrical properties compared to conventional fibers while at the same time retaining good textile and mechanical properties. The improved electrical properties result from the composition of the material. The material is generally composed mainly of polymers or polycondensates, but may also contain other polymers or monomers, or inorganic additives conventionally present in synthetic fiber materials to develop special properties. You can One example is a matte composition. Polymers in the present invention, a polymer compound obtained by polymerization, for example,
Not only polyolefins, polyacrylates, polyacrylonitrile, etc., but also those which can be produced by polycondensation, such as polyesters or polyamides, are used. The polymers and polycondensates mainly contained in the materials used according to the invention are, as measured in dichloroacetic acid at 25 ° C., generally an intrinsic viscosity of 0.45 to 1.2, preferably 0.
It has 6 to 0.9 dl / g.

The fiber-forming polymers or polycondensates of the materials used according to the invention can be melt-spun or solution-spun. Polymers that can be spun from solution by wet or dry spinning methods allow the use of less thermally stable charge control compounds.

A feature of one embodiment of the present invention is that the material contains a fiber-forming polymer selected primarily from the group comprising polyolefins, halogenated polyolefins, polyacrylates, polyacrylonitrile, polystyrene and fluoropolymers. That is.

Preferably, such materials are primarily selected from the group comprising polyethylene, polypropylene, polyacrylonitrile, polytetrafluoroethylene, and perfluorinated ethylene / propylene copolymers, especially those comprising polyethylene and polypropylene. Containing a fiber-forming polymer selected from

Another feature of another embodiment of the present invention is that the material is predominantly polyester, especially poly (alkylene terephthalate), eg poly (ethylene terephthalate), polycarbonates, aliphatic or aromatic polyamides, Polyimides, polyether ketones (eg PEK and PEEK), poly (arylene sulfides), especially poly (phenylene sulfide), polyacetals and cellulose esters, especially cellulose 2 (1/2) and triacetates. It contains a fiber-forming polycondensate selected from the group including.

The electret fibers according to the invention made from aromatic polyamides, polyetherketones (for example PEK and PEEK) and poly (arylene sulfides), in particular poly (phenylene sulfides), are in particular: Satisfies the requirement of improving chemical and / or thermal resistance.

A feature of a further preferred embodiment of the invention is that the material is a fiber whose material is selected mainly from the group comprising polyesters, polyetherketones and poly (phenylene sulfides), in particular poly (alkylene terephthalates). That is, it contains a polycondensation product. A feature of a further preferred embodiment of the present invention is that the material predominantly contains polypropylene. The polypropylene electret filaments and polyester electret filaments according to the invention are particularly preferred for use in the assembly of motor vehicles because of the single product aspect (easy recyclability).

The electret fiber material according to the invention is
For example, it contains a charge control compound as it is contained in a toner for electrophotography. A large number of charge control compounds for electrophotography are disclosed in the patent literature.

Therefore, the material is triphenylmethanes; ammonium and immonium compounds; ammonium fluoride and immonium compounds; biscationic acid amides; polymeric ammonium compounds; diallylammonium compounds; aryl sulfide derivatives Phenol derivatives; phosphonium compounds and fluorinated phosphonium compounds; calix (n) arenes; metal complex compounds; benzimidazolones; or as pigments, solvent dyes, basic dyes or acid dyes, listed in the Color Index The charge control compound contains one or various compounds selected from the group consisting of azines, thiazines or oxazines.

The charge control compound is preferably contained mainly in dispersed form in the fibrous material. This represents a multiphase system in which the material preferably forms a finely divided solid phase in which the charge control compound is finely distributed in the continuous phase of the fiber-forming polymer or polycondensate. "Predominantly" in the context of the present invention
The term means that a constant, usually small proportion of the charge control compound can also be truly dissolved in the fiber-forming polymer or polycondensate, i.e. the molecular distribution.
distiribution) to mean being present. The magnitude of this quantitative ratio obviously depends on the solubility of the charge control compound in the polymer or polycondensate. The lower limit of the average particle size of the dispersed charge control compound can be the lower limit of the colloidal distribution, ie, on average, at least one size of the particles is about 1 size or less.
have nm. This upper limit is generally about 20 μm.
In special cases, for example in the preparation of dispersions by precipitation operations or by special crystallization or grinding methods,
The charge control compound also has an average particle size of 1 nm or less or 2
It can also have a thickness of 0 μm or more. In special cases, the particle size of the dispersed charge control compound can be appropriately adjusted to give optimum charge stability. Obviously, dispersibility or redispersibility [ie primary particles and / or
Or non-aggregate of aggregates formed from aggregates (disiaggreg
ation]] and homogeneity of the dispersion also need to be taken into account appropriately.

In practice, particle sizes of 0.01 to 10 μm, in particular 0.03 to 1.0 μm, have proven useful for the charge control compounds dispersed in electret fibers according to the invention. The stability of the dispersion of the charge control compound contained therein under relatively long periods of time and / or under stressed conditions is also of particular importance for the application properties of the electret fibers according to the invention. Is. A narrower particle size distribution of the charge control compound in the electret fibers according to the invention is particularly preferred.

The charge control compounds which are contained individually or in combination with one another in the electret fibers according to the invention and which give the fibers very good electret properties are as follows:

1. Triarylmethane derivatives, eg: Color Index Pigment Blue 1, 1:
2, 2, 3, 8, 9, 9: 1, 10, 1
0: 1, 11, 12, 14, 18, 18, 19, 2
4, 53, 56, 57, 58, 59, 6
1, 62, 67, or, for example, Color Index Solvent Blue 2, 3, 4, 5, 6, 2
3, 43, 54, 66, 71, 72, 8
1, 124, 125, and where appropriate for their temperature stability and processability, triarylmethane compounds listed in the Color Index under Acid Blue and Basic Dies, such as Color Index Basic. Blue 1, 2, 5, 7,
8, 11, 15, 18, 20, 23, 2
6, 36, 55, 56, 77, 81, 8
3, 88, 89, Color Index Basic Greens 1, 3, 4, 9, 10 or Color Index Solvent Blues 125, 66 and 124 are particularly suitable. Color Index Solvent Blue 1 in its highly crystalline sulfate form
24 or trichlorotriphenylmethyltetrachloroaluminate is particularly suitable. Further examples of triphenylmethane series charge control compounds are very suitable for the production of electret fibers according to the invention, these compounds being described in DE-C-1 919 724 and DE-C-1 644 619. ing.

Also, triphenylmethanes as described in US-A-5 051 585, especially formula I:

[Chemical 1] [R ¹ and R ³ may be the same or different, and are —NH ₂ , a mono- or dialkylamino group, an alkyl group having 1 to 4 carbon atoms, preferably 1 or 2 carbon atoms, a mono group. -Or a di-ω-hydroxyalkylamino group, an alkyl group having 2 to 4 carbon atoms, preferably 2 carbon atoms, an unsubstituted or N-alkyl substituted phenyl- or phenylalkylamino group, a carbon atom 1 to
An alkyl group having 4, preferably 1 or 2, 1 to 4 carbon atoms in the aliphatic bridge, preferably
A phenylalkyl group having 1 or 2 and, in its phenyl nucleus, 1 or 2 of the following substituents:
Alkyl having 1 to 2 carbon atoms, alkoxy having 1 or 2 carbon atoms, and phenylalkyl group having a sulfonic acid group, R ² being hydrogen or the meaning defined for R ¹ and R ³ . Have one,
R ⁴ is hydrogen, halogen, preferably either chlorine or a sulfonic acid group, or, together with R ^5, form a fused phenyl ring, R ^5, together with R ^4, forms a fused phenyl ring, R ⁶ , R ⁷ , R ⁹ and R ¹⁰ are each
Hydrogen or an alkyl group having 1 or 2 carbon atoms, preferably a methyl group, R ⁸ is hydrogen or halogen, preferably chlorine, X ⁻ is a monovalent anion, especially chloride, It is a sulfate, molybdate, phosphomolybdate or borate anion. ] Is represented.

The charge control compound of formula 1 has the formula wherein R ¹ and R ³ are phenylamino, R ² is a m-methylphenylamino group, and R ^{4 to} R ¹⁰ groups are all hydrogen. Is particularly preferred.

2. Ammonium and immonium compounds as described in US-A-5 015 676.

3. Ammonium fluoride and immonium compounds as described in US-A-5 069 994, especially formula 3:

[Chemical 2] [Wherein R ¹ is a perfluorinated alkyl having 5 to 11 carbon atoms and R ² , R ³ and R ⁴ may be the same or different and may be 1 to 5 carbon atoms. , Preferably 1 to 2 alkyl, X ⁻ is
It is a monovalent anion, preferably the tetrafluoroborate or tetraphenylborate anion. Preferably R ¹ is a perfluorinated alkyl having 5 to 11 carbon atoms, R ² and R ³ are ethyl,
R ⁴ is methyl].

4. Biscationic acid amides as described in PCT-A-91 / 10172, especially of formula 4:

[Chemical 3] [Wherein R ¹ , R ² and R ³ may be the same or different and are an alkyl group having 1 to 5 carbon atoms, preferably methyl, and n is 2 to 5 And X ⁻ is a monovalent anion, preferably a tetraphenylborate anion. ] Is represented.

5. A diallylammonium compound as described in DE-A-4 142 541, especially of formula 5:

[Chemical 4] [In the formula, R ¹ and R ² may be the same or different and each is an alkyl group having 1 to 5 carbon atoms, preferably 1 or 2 carbon atoms, and particularly preferably a methyl group. , X ⁻ is a monovalent anion, preferably a tetraphenylborate anion. ] And a formula 6 obtainable therefrom, as described in DE-A-4 029 652 or DE-A-4 103 610:

[Chemical 5] [In the formula, n has a value corresponding to a molecular weight of 5,000 to 500,000. ] It is a high molecular weight ammonium compound represented by these. However, the molecular weight is 40,000 to 400,000.
Compounds of formula 6 having 00 are particularly preferred.

6. Aryl sulfide derivatives as described in DE-A-4 031 705, especially of formula 7:

[Chemical 6] [Wherein R ¹ , R ² , R ³ and R ⁴ are the same,
They may be different and have from 1 to 5 carbon atoms, preferably
R ⁵ is an alkyl group having 2 or 3 groups, R ⁵ is a divalent group, —S—, —S—S—, —SO— or —SO ₂
-Is one of. ] Is represented. For example, R
^{1 to} R ⁴ are propyl groups, and R ⁵ is a —S—S— group.

7. Phenol derivatives as described in EP-A-0 258 651, in particular of formula 8:

[Chemical 7] [Wherein R ¹ and R ³ are alkyl or alkenyl groups having 1 to 5 carbon atoms, preferably 1 to ³ carbon atoms, and R ² and R ⁴ are hydrogen or 1 to 3 carbon atoms.
Is an alkyl having 3 groups, preferably methyl, or where R ² and R ⁴ are hydrogen and R ¹ and R ³ are groups —CH ₂ —CH═CH ₂ . ] Is represented.

8. US-A-5 021 473 and US-A-5 147 748
Phosphonium compounds and fluorinated phosphonium compounds as described in Formula 9:

[Chemical 8] [Wherein R ¹ , R ² , R ³ and R ⁴ are the same,
They may be different and have 1 to 8 carbon atoms, preferably
It is an alkyl group having 3 to 6 and X ⁻ is a monovalent anion, preferably a halide anion. ] And the formula 10:

[Chemical 9] [In the formula, R ¹ is 5 to 15 carbon atoms, preferably 6
Is a highly fluorinated alkyl group having 10 to 10, R ² , R ³ and R ⁴ are alkyl or phenyl having 3 to 10 carbon atoms, and X ⁻ is a monovalent anion. is there. ] Is represented.

An exemplary example of a compound of formula 9 is tetrabutylphosphonium bromide, and an exemplary example of formula 10 is R ¹ ═C ₈ F ₁₇ —CH ₂ —CH ₂ —, R ² ═R ³ ═R
⁴ = phenyl, X ⁻ = PF ₆ − or tetraphenylborate anion.

9. Described in EP-A-0 385 580, also EP
-A-0 516 434 Calix (n) arenes [Calix (n) arenes], in particular Formula 11:

[Chemical 10] [Wherein, R is hydrogen, halogen, preferably chlorine, straight-chain or branched alkyl having 1 to 12 carbon atoms, aralkyl, such as benzyl or _{phenethyl, -NO 2, -NH 2, -NHR} 1 Or NR ¹ R ^{2 where} R ¹ is alkyl having 1 to 8 carbon atoms, unsubstituted or substituted phenyl or —Si (CH ₃ ) ₃ . ] Is represented.

10. Formula 12:

[Chemical 11] [Wherein M is a divalent or trivalent metal atom, preferably chromium, cobalt, iron, zinc or aluminum, Y and Z are divalent aromatic rings, preferably :

[Chemical 12] [Wherein, m is one of 1 and 2 and K ⁺ is a monovalent cation. ], Or again
Formula 13:

[Chemical 13] [Wherein M is a divalent or trivalent metal atom, preferably chromium, cobalt, iron, R ¹ is hydrogen, halogen, preferably Cl, nitro, or amidosulfonyl, R 1 ² is hydrogen or nitro, R
³ is hydrogen, a sulfonic acid group, -CO-NH-R ⁴ (wherein,
R ⁴ = phenyl, alkyl having 1 to 5 carbon atoms, which may be unsubstituted or substituted with mono-, di- or trialkylamino groups. ) And Z is a counterion which renders the complex neutral, preferably
Proton, alkali metal ion, or ammonium ion. ] Or the equation 14:

[Chemical 14] [In the formula, M is a divalent metal central atom, preferably a zinc atom, and R ¹ and R ² may be the same or different, and have 1 to 8 carbon atoms, preferably 3-6
A straight chain or branched chain alkyl group having, for example, t
-Butyl. ] A metal complex compound represented by, for example, a chromium azo complex, a cobalt azo complex, an iron azo complex,
Zinc azo complex or aluminum azo complex, or
It is a chromium salicylic acid complex, a cobalt salicylic acid complex, an iron salicylic acid complex, a zinc salicylic acid complex or an aluminum salicylic acid complex.

The above compound is EP-A-0 162 632, US-A-4 9
08 225, EP-A-0 393 479, EP-A-0 360 617, EP-A-0 291
930, EP-A-0 280 272, EP-A-0 252 925, EP-A-0 251 3
26, EP-A-0 180 655, EP-A-0 141 377, US-A-4 939 061,
It is described in US-A-4 623 606, US-A-4 590 141,
And / or CAS Nos. 31714-55-3, 104815-18-1,
84179-68-8, 110941-75-8, 32517-36-5, 38833-00-00,
95692-86-7, 85414-43-3, 136709-14-3, 135534-82-6,
135534-81-5, 127800-82-2, 114803-10-0, 114803-08-6
Characterized by

Examples of particularly preferred metal complex compounds of the above formula 13 are shown in the table below.

[0057]

[Table 1] 11. Benzimidazolones as described in EP-A-0 347 695, in particular of formula 15:

[Chemical 15] Wherein R ¹ is alkyl having 1 to 5 carbon atoms, R ² is alkyl having 1 to 12 carbon atoms, and X is a monovalent anion, especially chloride or tetrafluoro. A borate anion (an example that may be mentioned is R ¹ ═CH ₃ and R ² ═C ₁₁ H ₂₃ ). ] Is represented.

Alternatively, the following color index number: C.I. I. Solvent Black 5,5: 1, 5:
2, 7, 31 and 50; C.I. I. Pigment Black 1, C.I. I. Basic Red 2 and
C. I. Basic Black 1 and 2.

The material is preferably triphenylmethanes of formula 1; diallylammonium compounds of formula 5 and polymeric ammonium compounds of formula 6 obtained therefrom; arylsulfide derivatives of formula 7; It contains one or more different compounds selected from the group consisting of metal complex compounds as charge control compounds.

Formula 1 [wherein R ¹ and R ³ are phenylamino, R ² is 3-methylphenylamino, and X ⁻ is one sulfate ion equivalent. ] The material containing the compound as a charge control compound is particularly preferable as the electret fiber according to the present invention. This compound is
C. I. Known as Solvent Blue 124, the following formula 16:

[Chemical 16] Equivalent to.

Formula 5 or 6 wherein R ¹ and R ² are methyl and X ⁻ is the tetraphenylborate anion. ] The compound containing the compound as a charge control compound is also particularly preferable as the electret fiber according to the present invention.

Further, in the formula 7, R ¹ , R ² , R ³ and R ⁴ are propyl and R ⁵ is a disulfide bridge. Or a compound of the formula 13 [wherein R ¹ is
Chlorine, R ² is hydrogen and Z is a proton. ] The material containing the compound as a charge control compound is particularly preferable as the electret fiber according to the present invention.

The versatile possible uses of the electret fibers according to the invention are made possible by combining the above-mentioned material compositions with the textile fiber property data of the fibers to be achieved according to the conditions used during shaping. in this case,
It is surprising that electret fibers can be made with a spectrum of textile fiber properties that is apparently similar to fibers made from corresponding polymers without the addition of charge control compounds.

The electret fibers according to the present invention have
It has a range of 02 to 20 dtex. In the case of "split film fiber", average 0.02 to 30 dt
ex is useful and with it a little less coarse
It has fine fibers. 0.02-1 dtex, especially
Fibers having 0.02-0.5 dtex are preferably "split" technology [not to be confused with split film technology. ] Manufactured by In this case, a bicomponent fiber produced from an electret material and a solvent-soluble material having a "sea-island" cross section, the island-forming electret material is treated with a relevant solvent. The soluble part of the bicomponent fiber is dissolved, and extremely fine island fibers are obtained.

Further characteristics of the electret fibers according to the invention are that the tensile strength of the fibers is 20-80, preferably 30-65 cN / tex and the elongation at break is 10-.
200%, preferably 10 to 60%, particularly preferably 20 to 50%, and the heat shrinkage (S ₂₀₀ ) measured by drying at 200 ° C. is 0 to 50%, preferably <10%.
Is to be.

Textile fiber property data, tensile strength, elongation and heat shrinkage are conventionally controlled according to manufacturing requirements by setting spinning speed, drawing and heat setting conditions. Tensile strength 20-30cN / tex is
This is important for special applications where the fiber can be torn under constant load. Conventional textile fiber application areas require strengths of approximately 30-60 cN / tex. On the other hand, industrial fiber materials need to have high strength in the range up to about 80 cN / tex. Growth also depends on AISC (application
-specific). For industrial high-strength yarns, a low elongation of about 10-15% is required, for ordinary textile fiber applications, a fiber material with an elongation of about 20-40% is adopted, and special applications such as tertiary For the production of original deformable textile fiber sheets, yarns with as high extensibility as possible, for example up to 200% elongation, are desirable. The shrinkage of the fibrous material is adjusted to a value of 10% or less for conventional textile fiber applications, and for manufacturing staple fiber nonwoven webs, for example, <5%. However, certain high shrinkage fibers are also important for special applications, such as compression or crimping of textile fiber sheet materials.

The electret fiber according to the present invention has a content of 0 to
It may have a coating of 0.3% by weight, preferably 0 to 0.15% by weight of finish. Preferred embodiments of the finish-treated electret fibers according to the invention are those in which they are hydrophobic finishes, in particular waxes as hydrophobic agents, fluorinated surfactants and / or fluoropolymers such as polytetrafluoro. It has a hydrophobic finish containing ethylene.

As already mentioned above, the electret fibers according to the invention can be present in various forms as a linear or sheet-like product. In particular, they can be present in the form of multifilament yarns, tows and nonwoven webs.

The multifilament yarns according to the invention generally have capillaries of 20 to 500 dtex and 10 to 200 dtex, depending on the intended use, essentially giving the abovementioned textile fiber property values of the electret fibers according to the invention. Have. Obviously, the yarn can also be present as a mixed yarn with other synthetic or natural fibres, the non-electret fibers being not only their electrical properties, but also their conventional textile fiber properties, such as
It may differ from the electret fibers according to the invention in terms of tensile strength, elongation at break, shrinkage behavior and the like. This is especially important when special effects occur, such as high bulk effect, loop yarn yarn effect, core-sheath structure, etc., or when the fiber contains molten fibers so that the yarn stiffens when heated. is there.

Tows are multifilament skeins with thousands to millions of individual capillaries, the selection within this range being made for the intended end use.

The electret fibers according to the invention can also be supplied in the form of tows for further processing and processing steps such as crimping, drawing, heat setting, finishing, dyeing and the like. The electret fibers according to the invention can also be easily stored in the form of tows.

Nonwoven webs of electret fibers according to the invention represent a particularly valuable form of these fibers. These are described in more detail below. Their main area of application is in the production of very fine dust filters.

The electret fibers according to the invention can obviously also be present as bicomponent fibers in combination with non-electret materials. In this case, these are
For example, it can be present as a bicomponent fiber having a core-sheath structure having a core of an electret material having the composition as described in claim 1 and a sheath of a low melting point polymer material. The above fibers are particularly suitable for use in the production of endless fibrous nonwoven webs or staple fibrous nonwoven webs which can be bonded by heating.

The electret fiber according to the invention is also a bicomponent fiber having a core-sheath structure with a common fiber material, ie a core of spinnable polymeric material and a sheath of electret material of the composition specified above. Can exist as.

The electret fibers according to the invention can also be processed with other fibrous materials, such as patterned yarns or fused fibers, to give a nonwoven web, or they can be spun or blown to mix yarns, for example: Gives a commingle yarn.

In the present invention, it is possible to use a wet spinning method or a dry spinning method, which is a method known per se,
If necessary, the spun filaments are cooled and the fiber-forming material is spun from the melt or from a solution in a suitable solvent, about 100 to 8,000 m / min, preferably 1, The yarn is drawn at a speed of 000 to 5,000 m / min, followed by conventional processing steps, such as drawing if necessary, randomly depositing and combining, depending on the further application intended, yarns. Alternatively, in the method of producing an electret fiber according to the present invention, which comprises forming a tow, crimping and bulking, heat-setting, and chopping to form a staple fiber, an organic or organometallic charge control compound, mainly a fiber-forming polymer or A material containing a polycondensate, wherein the organic or organometallic charge control compound is 0.01 to 30% by weight, preferably 0.01 to 1 based on the weight of the material. 0% by weight, particularly preferably 0.1 to 5% by weight, comprising a spinning process.

Alternatively, the present invention may also be based on splitting a splittable multi-lobal fiber containing segments of electret material extending along the fiber axis, or where the island regions are from the electret material. In a process for producing electret fibers according to the invention, either by matrix dissolution of the composed "sea-island" filaments or by division of a film of electret material, an organic or organometallic charge control compound, mainly a fiber-forming polymer or polycondensate. And an organic or organometallic charge control compound, based on the weight of the material, 0.01 to 30% by weight, preferably 0.01 to 10% by weight, particularly preferably , 0.1 to 5% by weight of electret fiber.

Alternative methods for the production of electret fibers according to the invention useful are the fiber blowing method, as described in German patent application 19 64 060, or US Pat. No. 3,319,30.
"Flash spinning" as described in No. 9
Method, in each case the electret material used according to the invention is used.

During melt spinning, the electret material is heated to a temperature about 30-50 ° C. above the melting point of the polymer,
The melt is extruded through the spinneret as in conventional methods. The temperature of the melt is chosen within the ranges mentioned above so that an optimum flow of material is achieved which allows the shear forces required for the orientation of the filaments formed at spinning pressures which are not too high. For example, materials composed primarily of polypropylene are spun at about 260 ° C and polyester-based materials are spun at approximately 280-310 ° C.

When the polymer is spun from the melt, the filaments drawn from the spinneret orifice need to be solidified by cooling. Cooling can be done by any known method, allowing a special control of the filament properties in the processing of the electret material. Thus, for example, it is possible to delay the cooling by a reheater when producing fibers with special shrinkage / strength properties, and when producing self-crimping properties, cooling is very asymmetric. can do. On the other hand, so-called central cooling is particularly desirable, especially for producing individual filaments of less than 1 dtex, and this method ensures a particularly uniform and stress-free cooling of the filaments.

Spinning of the electret fibers according to the invention from a solution of the material in a suitable solvent can likewise be carried out according to known methods. In this case, in principle, the same conditions can be selected as for normal polymers. Solidification of the solution emerging from the spinneret can be carried out in dry spinning by evaporating the solvent or, in the case of wet spinning, precipitating the material in the form of filaments in a precipitation bath. In this case, in particular,
Good results are obtained with this material composition. That is, even a material containing a charge control compound which is not stable at the melting point of the polymer material can be used.

In the above-mentioned spinning method, in addition to a spinneret having a circular spinneret orifice, one having a modified orifice can also be used.
Side-disposed or core-sheath type multicomponent filaments can also be spun by special orifice arrangements or shapes known per se. Spin take-up speeds below 100 m / min. Are mainly used for producing yarns above 4 dtex. Spinning take-off speed 1,000-5,000
m / min. is more important economically, and in particular, fineness is
Very fine yarns are spun at maximum speeds in this range.

The production of the material to be spun according to the invention is carried out by uniformly incorporating the charge control compound into the polymeric material of which the material is mainly composed. in this case,
Using charge control compounds in the form of masterbatches,
Particularly preferred.

The spun filaments are generally subjected to drawing, the extent of which on the one hand is determined by the spinning orientation of the filaments, and on the other hand by the desired strength and extensibility. Spinning speed 1,000
The filaments obtained at m / min. and below require exclusively drawing when they are processed to form textile fiber yarn or sheet material. The degree of drawing required decreases continuously with increasing spinning speed, as these filaments already have a relatively fast spinning orientation. Therefore, a yarn with a very fine fineness spun at the maximum speed in this range is a fully drawn filament (so-called,
FOY) and does not require any post-stretching.

Where high strength filaments are to be produced, stretching to an elongation at break of approximately 10% and below has hitherto been carried out, especially filaments which are stretchable,
For example, for the production of sheet materials that can be deep drawn, the stretching is negligible, the extent of which is selected to yield an elongation at break of 200%. The filaments can be subjected to drawing in the form of multifilament yarns or in the form of tows.

The filament tension required for drawing is
It can be generated by godet or by a drawing jet or drawing duct. A godet pulls on a filament or thread by rubbing on a rotating godet surface, but in a drawing jet or drawing duct,
The filament is pulled by the strong air flow.
Of particular importance is the installation of stretch ducts in random non-woven webs, especially in the random deposition of filament material for the production of "spun-ponds".

Stretching can be carried out at room temperature or high temperature, especially at or above the glass transition point. So-called cold stretching is
In general, it produces special high shrink filaments, and high temperature drawing results in conventional shrinkage values of 0-10% suitable for textile production purposes.
Yielding filaments having Stretching of the filament material can be carried out in a known manner in a single step or multiple steps.

The electret fibers according to the invention can also be subjected to any known type of bulk crimping. Thus, the filaments, preferably in the form of a tow, are subjected to a stuffer box crimp, which, in the presence of relatively fine fiber bundles, may overfeed some of the fibers being fed. , Or not, can be swirled by vortexing jets to give more or less coherent thread, or, apart from this, give pattern thread, loop thread, or , These are either tentatively processed, or
It is subjected to processing by stretching. Other textile fiber related developments of multifilament yarns give bicomponent yarns where the onset of shrinkage results in a natural crimp when the electret fibers according to the invention are spun in combination with fibers having different shrinkages. The above-described side-by-side bicomponent fiber having an electret portion can also be crimped by selecting a constituent having different shrinkage characteristics from the electret material and initiating shrinkage.

A particularly preferred form for the electret fibers according to the invention is, as already mentioned above, in the form of a nonwoven web. That is, these non-woven webs are particularly effective when used for the production of extremely effective and particularly long-life dust filters, especially very fine dust filters.

When the fibrous material of the non-woven web contains or consists of electret fibers according to the invention, a high degree of textile fiber-related properties, in particular stability and very diverse composition, are found in the half-life of the charge. It was very surprising that it could be successfully combined with the enormous growth.

The subject of the present invention is therefore a non-woven web fabric, which is composed of or contains such synthetic fibers, the non-woven web fabric being at least partly according to the invention electret fibers. Composed of.

The amount ratio of electret fibers in the nonwoven web fabric, which gives it the desired combination of properties, is in some cases surprisingly small. At least 10%
Even in the case of non-woven web fabrics containing these electret fibers, significant economic and industrial advantages are often produced. Generally, electret fibers 50-10
It is appropriate to use a non-woven web fabric containing 0%, the profile which is the highest industrial requirement can obviously be met by a non-woven web fabric composed of 100% electret fibers.

The fineness values of the synthetic fibers of the non-woven web fabrics according to the invention and possibly of the products produced therefrom, especially the yarns in dust filters, are within the conventional range for these applications.

In some cases, in particular, in a nonwoven web cloth not composed of 100% electret fibers, it is appropriate to mix and use yarns having different fineness, and the electret fibers and the ordinary fibers have different finenesses. be able to.

The synthetic fibers may be endless filaments or staple fibers, suitably having a staple length of 0.2 to 200 mm. In this case, the non-woven web made of endless filaments is preferably present in the form of a non-woven fabric and staple fibers having a staple length of 20 mm or less are
Properly processed by wet deposition method, staple length 2
Staple fibers having a diameter of 0 mm and above are suitable for processing by carding and give non-woven webs.
However, it is also possible without difficulty to use a non-woven web fabric containing endless filaments and staple fibers. Thus, for example, in many cases, the desired combination of filament nonwoven web fabric properties, one of which is composed of endless filaments, can be tailored by compounding electret staple fibers in the proper proportions. Furthermore, it is also suitable to produce nonwoven webs of two or more types of electret fiber mixtures according to the invention, each type containing a different type of charge control compound as described above. Obviously, a mixture of electret staple fibers and regular staple fibers is deposited in random deposition to form spun fiber nonwoven webs.

This deposition can be carried out conventionally by dry or wet deposition. Dry deposition of staple fibers can generally be done on a card machine, and deposition of endless filaments can be done directly after spinning by the spunpond method. In this case, the spun filaments can further pass through a drawing duct, where they are drawn and accelerated to a preferred speed for deposition on the running screen. Immobilization of non-woven fabrics is generally performed by calendering freshly deposited filament webs.

Suitable synthetic fibers are generally composed of the spinnable polymers mentioned above, in particular polyamide, polyacrylonitrile, polyethylene, polypropylene or polyester. Synthetic fibers of polyester are preferable, poly (ethylene terephthalate) is particularly preferable, and polypropylene is also preferable.

The bonding (fixation) of the non-woven web cloth can be performed in principle by any known method. Thus, for example, the non-woven web can be impregnated with a binder, the non-woven web can be bound and then cured, or the binder can be incorporated into the non-woven web, for example in powder form or in the form of binding threads. May be a melt-bonding agent that binds and immobilizes the nonwoven web to form a nonwoven web fabric under the action of heat. Bonding (immobilizing) non-woven webs to form non-woven web fabrics can also be done by calendering, which in part results in mechanical felting of the filaments, in part, spontaneously at intersections. Cause melting. Apart from this, the melted adhesive material can obviously also be introduced into the nonwoven web as a constituent of side-by-side bicomponent fibers or as a sheath of core-sheath bicomponent fibers. Nonwoven web fabrics according to the present invention have proven to be preferable when mechanically bonded (fixed). Mechanical coupling or immobilization means, for example, needling, or aside from this,
As described in EP-A-0 108 621, for example, to mean a hydromechanical bond. Various bonds,
A combination of immobilization or stiffening methods can also be performed if desired.

The weight per unit area of the non-woven web fabric according to the invention obviously depends on the intended use. Generally, this is from 5 to 300 g / m ² , preferably 100 to
250 g / m ² , but may be higher, for example up to 1000 g / m ² , for special purposes.

Another preferred embodiment of the non-woven web fabric according to the invention is a spun pond fabric, in particular a non-woven fabric fixed by needling or a melt adhesive, or a dry type bonded and fixed by a melt adhesive. Alternatively, it is a wet applied staple fiber non-woven web cloth. If necessary, the non-woven web cloth is
Also, similarly, is composed of electret fibers,
Alternatively, another textile fiber material containing them, for example another nonwoven web fabric or similarly composed of electret fibers, or a textile fiber material of a given yarn layer containing them. It can also be combined. In particular, a combination of a support and a reinforced textile fiber material, or one which functions as a protective coating, is often desired. In a preferred embodiment, the electret fiber-containing non-woven web according to the invention is covered with a protective textile fiber material, such as a non-woven web fabric, in particular a fine non-woven web, on one side or, in particular, on both sides. To do. In particular,
For use of the nonwoven webs according to the invention as dust filters, it is often useful to combine coarse or deep filters.

The invention can also be based on the random deposition of synthetic endless filaments or staple fibers in a manner known per se on moving supports, or [“Radko Krcema, Handbuch der Textilverbundsto.
ffe (handbook of composite textile fabrics), Deutsc
See her Fachverlag GmbH (1970), page 53. ] Alternatively, a nonwoven web is formed from the staple fibers by a carding machine and subsequently bonded. A method of making a nonwoven web fabric according to the invention, characterized in that at least some of the deposited synthetic fibers are electret fibers.

According to the invention, in the production of nonwoven web fabrics of spun fibers containing a certain proportion of electret fibers, the mixture of electret fibers and conventional staple fibers in the desired mixing ratio is known per se. The non-woven web is formed by the dry or wet deposition method of the above method, and subsequently bonded (immobilized). However, it is also possible to produce a nonwoven web fabric from endless filaments and staple fibers by adding staple fibers during the deposition of the endless filaments. In this case, if desired, the endless filaments or staple fibers can be composed wholly or partly of electret fibers. In the production of nonwoven web fabrics by the spunpond method, it is also possible to mix regular and electret fibers during the deposition. For this purpose, for example, electret fibers are produced separately, collected in a fiber reservoir, for example from a bobbin frame, blown in a jet stream and fed into the fiber stream of normal fibers for deposition, or Apart from the spinneret orifices for normal fibers, it also allows the spinning beam, which serves for producing the nonwoven web filaments, to have spinneret orifices for electret fibers, the ratio of various spinneret orifices and The amount of filaments spun can also correspond to the desired ratio of normal to electret fibers in the nonwoven web fabric.

Generally, for the production of the nonwoven web fabrics according to the invention, at least 10% by weight of electret fibers are deposited or a fiber mixture containing at least 10% by weight of electret fibers is processed by carding. To form a nonwoven web.

The quantity ratio of the electret fibers deposited is
Preferably, it is 50-100%, and 75-100% of the deposited fibers are electret fibers in order to achieve maximum effect.

In order to fix the non-woven web to form the non-woven web cloth, a binder or a melt binder is used, or calendering is performed by a method known per se, or preferably mechanically. By any means. However, it is also possible to combine several of these immobilization methods.

The binder may be, for example, a polymer solution or dispersion or latex, which is applied to the nonwoven web by impregnation or spraying and, after evaporation of the liquid phase, a drop-like bond at the intersection of the filaments. Form a point. However, it is also possible to use thermosetting plastic binders, which presumably cure in the heat treatment and fix the fiber crossing points. The melt binder, for example, in the form of a powder, preferably in the form of a binding fiber, is mixed in the nonwoven web, and when the nonwoven web is heated to its melting point or higher, it is bonded at the fiber crossing point to form a bonding point, This immobilizes the non-woven web after cooling to form a non-woven web fabric, which can be used with great success.

Similar compression can be achieved by "voluntary" melting of the nonwoven web filaments at their intersections when the nonwoven web is calendered at temperatures near the melting point of the nonwoven web filaments.

Mechanical immobilization, eg EP-A-0 108 621
Good results are also obtained, for example, by needling, or by hydromechanical immobilization, as described in US Pat. In this case, the chemical or thermal stress of the filament material does not occur and the favorable physical properties imparted to the filament by these manufacturing conditions, such as high speed spinning and drawing operations, are not diminished and the nonwoven web fabric is not reduced. Be transmitted to.

In order to bring about the combination of the nonwoven web fabric according to the invention with the textile fiber material of a given yarn ply, the nonwoven web textile is made so that delamination does not occur in this textile fiber material. Need to be combined. This requirement is best met when the components are combined by needling, glueing or stitching.

Weft-lapping technology
The production of such composite fabrics by the Raschel technique) is particularly preferred. This is a warp knitting technique in which a yarn, preferably high strength yarn, with or without electret fibers, made of electret fibers, strengthens the nonwoven web fabric in a particular direction.
(warp-knitting technique). This warp knitting technique can be carried out on so-called Raschel machines. A particularly suitable Raschel machine for the production of composite fabrics formed according to the invention is the company Karl Mayer, Textilmaschi.
It is a type RS 3 MSU-V manufactured by nenfabrik GmbH, Obertshausen.

Nonwoven webs composed of electret fibers according to the invention or containing them in an effective amount ratio have already been mentioned above, which is especially suitable for the production of very fine fabric filters. preferable. The subject of the invention is therefore also this application of electret and textile fiber materials, in particular the nonwoven web fabrics containing them.

For manufacturing reasons, it is preferred to provide the fibers with the antistatic finish at the end of the manufacturing process, for example after filter manufacture, prior to forming the nonwoven web, which need only be washed off. It was very surprising that in many cases in the production of nonwoven webs it was shown in this context that the antistatic agents used were usually only highly diluted finishes or water. This embodiment of the manufacturing method is, in particular, environmentally acceptable. The filter is then electrostatically charged, for example with a corona discharge. Furthermore, in the production of nonwoven webs from the electret fibers according to the invention on a card machine or in their use as filters, the passage of gas ensures that sufficient charging of the nonwoven web is already achieved, often by the triboelectric effect. And it was a great surprise to show that it does not have to spend a separate charging step.

The following examples illustrate the practice of the invention.

[0114]

EXAMPLE 1 A poly (ethylene terephthalate) fiber raw material modified by thoroughly mixing a charge control compound of formula 16 (CI Solvent Blue 124) in the form of a masterbatch was prepared according to the present invention as Solvent Blue 124. The concentration was 0.5% by weight of the spun material. In this case, a masterbatch is produced from a charge control compound having a high crystalline form,
The X-ray (Cu-Kα radiation) diagram of the compound is
Strong reflection at 2δ ° = 18.47, 2δ ° = 6.97;
Three moderately strong reflections at 12.1 and 13.9, 2δ ° = 20.0; 21.7; 22.5; 2
It showed weak and broad reflections at 4.8; 28.2; 30.7 and 32.2.

The material thus produced was spun by conventional melt spinning techniques. The spinning temperature was 285 ° C., and the spinning take-off speed was 1500 m / min.

The spun material produced was likewise processed by conventional production line techniques (stuffer box crimping, heat setting and chopping) to give individual fibers of 1.3 d
A wooly staple fiber modified according to the invention having tex was provided.

From the modified staple fibers produced, and of these fibers, in each case 20% by weight of the binding fibers (type: core melting point 110 ° C., core having 3 dtex). Two-component fiber polyester / copolyester in a sheath structure and normal fibers (likewise normal fibers have 1.3 dtex).
A non-woven web was produced in a laboratory card machine from a mixture of In this case, the varied parameter was the ratio of the weight per unit area (m) of the nonwoven web to the amount of ordinary fiber. Immobilization of the nonwoven web was carried out thermally at 160 ° C. and the residence time was 3 minutes.

The separation efficiency of the produced nonwoven webs was tested in a conventional filter test stand operated by the light scattering measurement principle.

The following test parameters were set.

Flow rate: 20 cm / sec, each pressure difference PD given below varied with particle mass concentration: 50 mg / m ³ , dust collision time: 1-3 minutes, test dust: having the following composition ac fine: ”

[Table 2] ● Sample 1: m = 200 g / m ² ; PD = 23 Pa; 80% by weight of fiber modified according to the present invention; 20% by weight of bicomponent binding fiber ● Sample 2: m = 200 g / m ² ; PD = 26 Pa; 40% by weight of fibers modified according to the present invention; 40% by weight of ordinary fibers; 20% by weight of bicomponent binding fibers ● Sample 3: m = 200 g / m ² ; PD = 25 Pa; 80% by weight of ordinary fibers %; Two-component binding fiber 20% by weight ● Sample 4: m = 100 g / m ² ; PD = 10 Pa; Fiber modified by the present invention 80% by weight; Two-component binding fiber 20% by weight ● Sample 5: m = 100 g / m ² ; PD = 10 Pa; 80% by weight of normal fiber; 20% by weight of bicomponent binding fiber ● The separation efficiency achieved by these nonwoven web samples is given in the table below.

[0121]

[Table 3]

[Table 4]

[Table 5]

[0122]

Example 2 As in Example 1, a poly (ethylene terephthalate) fiber feedstock was modified according to the invention with a charge control compound of formula 16 (CI Solvent Blue 124).
The mixing was done as in Example 1, but sufficient masterbatch was used here so that the concentration of Solvent Blue 124 was 1.0% by weight in the spun material. Also in this case, the highly crystalline form of the charge control compound used in Example 1 was used.

The material thus obtained was spun as in Example 1 to produce 1.7 dtex fibers in this case. A nonwoven web having a weight per unit area of 200 g / m ² and a bonded fiber content of 20% by weight (two-component fiber as in Example 1) was produced from the fibrous material, as described in Example 1. The nonwoven web was fixed. The nonwoven web thus obtained is hereinafter referred to as Sample 6. For comparison, a non-woven web was prepared from poly (ethylene terephthalate) unmodified with Solvent Blue 124 under exactly the same spinning and non-woven forming conditions. This nonwoven web is hereinafter referred to as Sample 7.
The separation efficiencies of these two nonwoven web samples are compared with each other and are shown in Table 6 below.

[0124]

[Table 6] Table 6 shows, among other things, the considerable improvement in the separation efficiency of fine dust after a relatively long dust impact time, which is achieved by using the nonwoven web material according to the invention.

Table 7 below shows that the nonwoven web material according to the invention surprisingly retains a very good separation efficiency, even after discharge by water treatment, without external charging. Show.

[0126]

[Table 7]

[0127]

Example 3 Instead of the charge control compound of formula 16 used in Example 1, R ¹ and R ² are methyl groups,
X ⁻ is tetraphenylborate anion, and its average molecular weight determined by solution viscosity measurement is about 300,
000 and having one of the compounds of formula 6 having a melting point / decomposition point of 225 ° C., the rest of the working procedure being exactly as in Example 1.
The filter material was similarly obtained with good separation efficiency. The charge control compound of Formula 6 used in this example can be prepared as described in Preparation Example 3 of DE-A-4 103 610. Table 8 below shows the separation T (x) of the nonwoven web fabric filter obtained with this discharge control compound according to the invention.

[0128]

[Table 8]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location D04H 1/42 Z 7199-3B 13/00 7199-3B D06M 10/00 (72) Inventor Hans- Tobias Makholt Germany Day-64297 Darmstadt, Waldstraße 20 (72) Inventor Peter Boening Germany Day-65197 Wiesbaden, Erbacher Strasse 2

Claims (32)

[Claims] 1. An electret fiber having improved charge stability, which is composed of a material containing an organic or organometallic charge control compound and mainly a fiber-forming polymer or polycondensate, said organic or organometallic The charge control compound is 0.01 to 30% by weight, preferably 0.01 to 30% by weight based on the weight of the material.
-10 wt%, particularly preferably 0.1-5 wt% electret fiber. 2. The fiber-forming polymer or polycondensate is
The electret fiber according to claim 1, which is melt-spinnable. 3. The fiber-forming polymer or polycondensate is
The electret fiber according to claim 1, which is solution-spinnable. 4. The fiber-forming polymer selected from the group consisting of polyolefins, halogenated polyolefins, polyacrylates, polyacrylonitrile, polystyrene and fluoropolymers. The electret fiber according to any one of 1. 5. The material is mainly polyethylene,
An electret fiber according to any of claims 1 to 4, containing a fiber-forming polymer selected from the group comprising polypropylene, polyacrylonitrile, polytetrafluoroethylene, and perfluorinated ethylene / propylene copolymers. 6. The electret fiber of claim 5, wherein the material comprises a fiber-forming polymer selected from the group consisting primarily of polyethylene and polypropylene. 7. The material is mainly polyesters, polycarbonates, aliphatic or aromatic polyamides, polyimides, polyether ketones (eg P
EK and PEEK), poly (arylene sulfide)
The electret fiber according to any one of claims 1 to 3, which contains a fiber-forming polycondensate selected from the group consisting of a group, particularly poly (phenylene sulfide), polyacetals, and cellulose esters. 8. The material of any one of claims 1-3 and 7, wherein the material comprises a fiber-forming polycondensate selected from the group consisting primarily of polyesters, polyetherketones and poly (phenylene sulfide). The electret fiber according to. 9. The electret fiber according to claim 8, wherein the material mainly contains poly (alkylene terephthalate). 10. The electret fiber according to claim 1, wherein the material mainly contains polypropylene. 11. The charge control compound as claimed in claim 1, wherein the material comprises a charge control compound as contained in a toner for electrophotography.
10. The electret fiber according to any one of 10 to 10. 12. The material is triphenylmethanes;
Ammonium and Immonium Compounds; Ammonium Fluoride and Immonium Compounds; Biscationic Acid Amides; Polymeric Ammonium Compounds; Diallylammonium Compounds; Aryl Sulfide Derivatives; Phenol Derivatives; Phosphonium Compounds and Fluorinated Phosphonium Compounds; Calix (n) arenes; metal complex compounds; benzimidazolones; or from the group of azines, thiazines or oxazines listed in the Color Index as pigments, solvent dyes, basic dyes or acid dyes The electret fiber according to any one of claims 1 to 11, which contains one or various selected compounds as a charge control compound. 13. The material is triphenylmethanes of formula 1; ammonium compounds and immonium compounds of formula 2; ammonium fluorinated compounds of formula 3 and immonium fluorinated compounds; biscationic acids of formula 4. Amides; diallylammonium compounds of formula 5;
Polymeric ammonium compounds of formula 6 obtained therefrom;
Aryl sulfide derivatives of formula 7; Phenol derivatives of formula 8; Phosphonium compounds and fluorinated phosphonium compounds of formulas 9 and 10; Calix (n) arenes of formula 11; Metal complex compounds of formulas 12, 13 and 14; Benzimidazolones of formula 15; azines with the following color index numbers: C.I. I. Solvent Black 5, 5: 1, 5: 2, 7, 31 and 50; I. Pigment Black 1, C.I. I. Basic Red 2, C.I. I. Basic Black 1 and 2, and C.I. I. Oxidation 1; Thiazines having the following color index numbers: C.I. I. Basic Blue 9, 24 or 25, and C.I. I.
Solvent Blue 8; Oxazines with the following color index numbers: C.I. I. Pigment Violet 2
3, C.I. I. Basic Blue 3, 10 or 1
2; or, if they allow the spinning and manufacturing temperatures of the electret material, the azines, thiazines and oxazines listed under the name of basic or acid dyes in the color index; The electret fiber according to any one of claims 1 to 12, containing one or various compounds selected from the group consisting of as a charge control compound. 14. The material is triphenylmethanes of formula 1; diallylammonium compounds of formula 5 and polymeric ammonium compounds of formula 6 obtained therefrom; arylsulfide derivatives of formula 7; metals of formulas 12 and 13 Containing, as a charge control compound, one or more different compounds selected from the group consisting of complex compounds.
The electret fiber according to any one of claims 1 to 13. 15. The material has the formula 1 [wherein R ¹ and R ³
Is phenylamino, R ² is 3-methylphenylamino, and X ⁻ is one sulfate ion equivalent. ]
The electret fiber according to any one of claims 1 to 14, containing a compound represented by the formula as a charge control compound. 16. The material has the formula 5 [wherein R ¹ and R ²
Is methyl and X ⁻ is the tetraphenylborate anion. ] The electret fiber in any one of Claims 1-15 containing the compound represented by this as a charge control compound. 17. The material has the formula 7 [wherein R ¹ , R ² ,
R ³ and R ⁴ are propyl and R ⁵ is a disulfide bridge. ] The electret fiber in any one of Claims 1-16 containing the compound represented by this as a charge control compound. 18. The material is represented by Formula 13 [wherein R ¹ is
Chlorine, R ² is hydrogen and Z is a proton. ] The electret fiber in any one of Claims 1-17 containing the compound represented by this as a charge control compound. 19. The electret fiber is 0.02.
The electret fiber according to any one of claims 1 to 18, which has -15 dtex. 20. The tensile strength of the fiber is 20 to 8
0, preferably 30 to 65 cN / tex, elongation at break 10 to 200%, preferably 10 to 50%, particularly preferably 20 to 30%, and heat shrinkage measured by drying at 200 ° C. The rate (S ₂₀₀ ) is 0 to 50%, preferably
The electret fiber according to any one of claims 1 to 19, which is <10%. 21. The electret fibers are 0 to 0.
The electret fiber according to any one of claims 1 to 20, to which 3% by weight, preferably 0 to 0.8% by weight of a finishing agent is applied. 22. The electret fiber according to claim 1, wherein the electret fiber is present in the form of multifilament yarn, tow and nonwoven web. 23. The electret fiber according to claim 1, wherein the electret fiber is present as a two-component fiber in combination with a non-electret material. 24. The electret fiber according to claim 1.
The electret fiber according to any one of claims 1 to 23, which is present as a bicomponent fiber having a core-sheath structure of a core of the electret material of the composition described in (1) and a sheath of a low melting point polymer material. 25. The electret fiber is present as a bicomponent fiber having a core-sheath structure of a core of a spinnable polymeric material and a sheath of an electret material of the composition according to claim 1. The electret fiber according to any one of 24. 26. The electret fibers are 0 to 0.
26. The electret fiber according to any of claims 1 to 25, wherein 3% by weight, preferably 0 to 0.15% by weight of a hydrophobic finish is applied. 27. It is possible to use wet spinning or dry spinning as it is known per se, if necessary cooling the spun filaments to remove the fiber-forming material from the melt or , From a solution in a suitable solvent, spun to about 100-8,000 m / min, preferably 1.0
The yarn is drawn at a speed of 0,000 to 5,000 m / min, followed by conventional processing steps, such as drawing if necessary, randomly deposited and combined, depending on the further intended use, yarns. Alternatively, in the method for producing an electret fiber according to claim 1, wherein a tow is formed, crimped and bulked, heat set, and shredded to form a staple fiber, an organic or organometallic charge control compound, mainly a fiber. A material containing a forming polymer or a polycondensate, wherein the organic or organometallic charge control compound is 0.01 to 30% by weight, preferably 0.
01 to 10% by weight, particularly preferably 0.1 to 5% by weight
A method comprising spinning something that is. 28. A matrix of sea-island filaments, either by splitting a splittable multi-lobal fiber containing segments of electret material extending along the fiber axis or in which the island regions are composed of the electret material. The method for producing an electret fiber according to claim 1, wherein the electret material contains an organic or organometallic charge control compound and mainly a fiber-forming polymer or a polycondensate, by dissolution or by division of an electret material film. Therefore, the organic or organometallic charge control compound has a concentration of 0.
A method comprising an electret material which is 01 to 30% by weight, preferably 0.01 to 10% by weight and particularly preferably 0.1 to 5% by weight. 29. A nonwoven web fabric composed of or containing the electret fibers of claim 1. 30. A dust filter composed of or containing the non-woven web fabric of claim 29. 31. Use of electret fibers according to claim 1 for the production of non-woven web fabrics. 32. Use of the electret fiber according to claim 1 for the production of dust filters.